1. Field of the Invention
This invention relates generally to devices for preventing the accidental or unintentional discharge of a firearm, and particularly to a passive safety mechanism that provides a locking capability.
2. Prior Art
Various types of active locking mechanisms for firearms are known. These mechanisms include: (1) bore locks which require the insertion of a lockable bar through the bore or barrel of the firearm, (2) trigger guard locks that enclose the trigger guard area to prevent insertion of a finger or block rearward movement of the trigger itself, and (3) frame-mounted locks which integrate an active locking mechanism into one or more operations of the firearm, such as the manual safety, hammer drawback or drop, or magazine insertion.
Representative examples of various frame-mounted active locking mechanisms are shown in U.S. Pat. Nos. 3,673,725 to Cravener; 3,882,622 to Perlotto; 4,014,123 to Williams; 4,136,475 to Centille; 4,384,420 and 4,532,729 to Von Muller; 4,763,431 to Allan; and 5,140,766; 5,090,148; and 4,987,693 to Brooks.
The Perlotto '622 patent discloses a locking mechanism particularly suited for semi-automatic pistols incorporating a hammer-blocking manual safety and a manual de-cocking mechanism, although that reference does not discuss the structure and operation of the "shaft" on which the manual safety lever is carried in relation to its functions in retaining the firing pin, blocking the hammer from contacting the firing pin when the manual safety is "on," interrupting the trigger pull or hammer release mechanisms, and preventing manual insertion or release of the magazine.
The Perlotto '622 active locking mechanism is operated utilizing a key which acts to rotate a cam that has an arcuate circumferential surface aligned with one half of the face of a spring-biased retractable pin. The cam has an angularly-oriented face which defines an orthogonal notch or recess facing the closely confronting end of the shaft and opposing the keyway. (The keyway therefore opposes the thumb-actuated safety lever relative to the frame of the semi-automatic pistol.) The interface between that cam and the confronting end of the shaft is aligned generally along the longitudinal axis of that retractable pin, with one half of that retractable pin being received within a groove or locking recess formed in the semi-circular projection extending from the end of the shaft confronting the cam, and the remaining half of the retractable pin being received within the orthogonal notch. Rotation of the key and cam through a quarter revolution (90.degree.) to the "unlocked" position causes the angularly-oriented face of the cam to depress the retractable pin into the aligned bore in the frame to a point where the face of the retractable pin is at least flush with or spaced apart from the circumferential surface of the shaft on which the manual safety lever is mounted. The manual safety lever may then be pivoted to its "off" position, thus allowing a round of ammunition to be chambered from the magazine and the pistol to be fired. Depressing the retractable pin thereby pushes the retractable pin out of the locking recess to prevent that pin from obstructing the rotation of the shaft, and the manual safety lever can be pivoted back and forth to disengage or engage the safety as desired until the cam is subsequently rotated to the "locked" position, releasing the retractable pin into the locking recess and obstructing the rotation of the shaft and movement of the manual safety lever. Rotation of the cam to the "locked" position also disposes one surface of the orthogonal notch to a mating position with the corresponding surface on the projecting end of the shaft, further preventing rotation of the shaft.
The Perlotto '622 active locking mechanism does present several noteworthy limitations and drawbacks. First, although Perlotto '622 does constitute an active locking mechanism, the extension from the cam which the key engages is exposed through the keyway and can easily be manipulated or rotated by a person using a pliers, screwdriver, allen wrench, or similar tool depending upon the cross-sectional shape of the extension. As such, the Perlotto '622 locking mechanism is especially susceptible to circumvention or unauthorized use, and the exposed extension invites curiosity.
Perlotto '622 depicts a right-handed embodiment of the active locking mechanism. The keyway must necessarily be disposed on the opposite side of the frame from the thumb-actuated safety lever, thereby placing the keyway on the opposite side of the pistol from the shooter's free left hand. In order to place the key in the keyway and rotate the cam using the left hand while still gripping the pistol in the shooting hand, the pistol must be turned over (thus reversing the orientation for the conventional rotation of the key and lock) or inwardly toward the shooter's torso. These motions require extensive practice to perform smoothly, and can be time-consuming and dangerous in an emergency or life-threatening situation where a person may not think clearly or react calmly. The alternative is to shift the pistol to the non-shooting hand, which is again time consuming and dangerous for a person who lacks the proper training or is involved in an emergency or life-threatening situation.
Moreover, once the active locking mechanism has been disengaged, the firearm is returned to its normal mode of operation and is rendered equivalent to a firearm without a locking mechanism. A person is therefore as apt to engage the manual safety and set the firearm down, or place the firearm in storage without engaging the active locking mechanism, as they would be with a conventional firearm lacking any locking mechanism. To overcome this disadvantage, the active locking mechanism could be modified to lock the firearm each time the manual safety is engaged. However, a person might accidentally or unintentionally engage the manual safety in a situation where the firearm might be needed imminently, and the unlocking operation would then need to be repeated before the firearm could be fired.
The Perlotto '622 active locking mechanism also requires a retaining cap to enclose the elements of the locking mechanism that extend outwardly beyond the side of the slide assembly or frame. This requires either an extensive modification to the slide assembly design or else welding a cap over the locking mechanism, since a threaded cap and aperture could easily be removed to circumvent the locking mechanism.
Finally, the prevailing trend in the manufacture of semi-automatic pistols is to utilize an ambidextrous manual safety, and in many models an integrated de-cocking mechanism. However, the Perlotto '622 active locking mechanism requires that the slide assemblies and manual safeties be completely redesigned and re-tooled for each model of firearm incorporating the locking mechanism. Distinct frames, slide assemblies, and safeties must be fabricated for right- and left-handed firearms, and the orientation of the cam and shaft surfaces would also need to be reversed if the manual safety is disposed on the opposite or left-handed side of the firearm. This greatly increases the cost and complexity of manufacturing and implementing the Perlotto '622 locking mechanism in commercial firearms.
Moreover, the shaft on which the manual safety lever is carried in many semi-automatic pistols is the firing pin retainer, which has surfaces or detents which engage and interact with the firing pin safety lever and the ejector/magazine depressor lever, none of which are shown or discussed in Perlotto '622. Consequently, due to the placement of the firing pin safety lever and the ejector/magazine depressor lever, the Perlotto '622 locking mechanism could not be incorporated into both left- and right-handed firearms of this type without effectively creating two separate "mirror-image" firearms.
In any event, the Perlotto '622 design could not be incorporated into many of these modern semi-automatic pistols because insufficient space is permitted to place the cam and retractable pin in the area of the firing pin retainer. The thin walls of conventional slide assemblies do not permit a bore to be machined to hold the spring and retractable pin while still maintaining the integrity of the slide assembly, and many models of semi-automatic pistols utilize a larger diameter firing pin that consumes most of the free space in the rear block of the slide assembly. The location of the firing pin safety lever and the ejector/magazine depressor lever also prevents the cam and retractable pin from being placed on either side of the firing pin in many semi-automatic pistols.